Projections from the International Energy Agency show global energy demand growing by close to 30 percent by 2020, setting the stage for massive growth in the carbon dioxide emissions that are warming our planet. But dramatically ramping up energy efficiency would allow the world to not only avoid growth in energy demand but actually reduce global demand to below 2006 levels by 2020.

We can reduce the amount of energy we use by preventing the waste of heat and electricity in buildings and industrial processes and by switching to efficient lighting and appliances. We can also save an enormous amount of energy by restructuring the transportation sector. Many of the needed energy efficiency measures can be enacted relatively quickly and pay for themselves.

Buildings are responsible for a large share of global electricity consumption and raw materials use. In the United States, buildings account for 70 percent of electricity use and close to 40 percent of total CO2 emissions. Retrofitting existing buildings with better insulation and more-efficient appliances can cut energy use by 20 to 50 percent. A U.S.-based group of forward-thinking architects and engineers has set forth the Architecture 2030 Challenge, with the goal of reducing fossil fuel use in new buildings 80 percent by 2020 on the way to going entirely carbon-neutral by 2030.

Lighting also offers great opportunities for improving efficiency. Much of the energy we use for lighting today is wasted as heat rather than used for illumination, so switching to more-efficient lighting can have a quick payback. Swapping out conventional light bulbs for energy-efficient compact fluorescent lamps (CFLs), for example, can cut energy use by 75 percent, saving money on electric bills. And CFLs last up to 10 times as long. The energy saved by replacing one conventional incandescent 100-watt bulb with a CFL over its lifetime is enough to drive a Toyota Prius hybrid from New York to San Francisco. If everyone around the world made the switch and turned to high-efficiency home, office, industrial, and street lighting, total world electricity use would fall by 12 percent, equivalent to the output of 705 coal-fired power plants.

Similar efficiency gains can be realized with household appliances. Take refrigerators, for instance. The average refrigerator in Europe uses about half the electricity of one in the United States. Beyond that, the most efficient refrigerators on the market use one fourth as much electricity as the European average.

Japan’s Top Runner Program takes the most efficient appliances on the market today and uses them to set the efficiency standards for tomorrow. Between 1997–98 and 2004–05, this program helped Japan boost the efficiency of refrigerators by 55 percent, air conditioners by close to 68 percent, and computers by 99 percent. This sort of program, which continuously encourages technological advancements, can serve as a model for the rest of the world.

Even the electricity drawn by appliances in “standby” mode, when they are not actively turned on, currently adds up to as much as 10 percent of total residential electricity consumption. Industry standards, like South Korea’s 1-watt standby limit for many appliances that will go into effect by 2010, push manufacturers toward energy-efficient design. Consumers can eliminate unnecessary electricity drain by unplugging electronics or by using improved “smart” power strips to stop electricity flow to appliances that are not in use.

Within the industrial sector, retooling the manufacture of the carbon emissions heavyweights—chemicals and petrochemicals (including plastics, fertilizers, and detergents), steel, and cement—offers major opportunities to curb energy demand. Recycling plastics and producing them more efficiently could cut petrochemical energy use by close to one third. More than 1 billion tons of steel are produced each year to be used in automobiles, household appliances, construction, and other products. Adopting the most-efficient blast furnaces and boosting recycling can cut energy use in this industry by close to 40 percent. For cement, the biggest gains can come from China, which produces close to half of the world’s 2.3 billion ton output—more than the next 20 countries combined. Just shifting to the most efficient dry kiln technologies, as used in Japan, could cut global energy use in the cement sector by more than 40 percent.

Well-designed transportation systems also play a prominent role in increasing energy efficiency. The car-dominated systems that at first offered mobility now more frequently yield congestion and pollution. Restructuring urban transportation systems around rail, light rail, and bus rapid transit (with designated lanes for buses), while making safety and accessibility for pedestrians and bicyclists a priority, not only deals with the problems created by the “car-is-king” mentality, it also saves energy.

Much of the energy savings in the transport sector come from electrifying rail systems and short-distance road travel, while turning away from petroleum products and toward renewable sources of energy. Mass transit is key. Intercity high-speed rail lines, as seen in Japan and Europe, can move people quickly and energy-efficiently, reducing car and air travel.

For personal vehicles, improved fuel economy is key. Plug-in hybrid electric vehicles (PHEVs) running primarily on emissions-free electricity generated by the wind and the sun would allow for low-carbon short-distance car trips. While most commuting and errands could be done solely on battery power, a backup fuel tank would allow for longer trips. Among the companies planning to come to market with a PHEV in the next several years are Toyota, General Motors, Ford, and Nissan. Combining a shift to PHEVs with widespread wind farm construction to supply electricity would greatly reduce oil consumption and carbon emissions and would allow drivers to recharge batteries with renewable electricity at a cost equivalent of less than $1 per gallon of gasoline.

Overall, investing in energy efficiency to offset increasing energy demand is often cheaper than expanding the energy supply to meet that demand. Efficiency investments typically yield a high rate of return and can help fight climate change by avoiding additional CO2 emissions.

In stark contrast to the International Energy Agency’s projected 30 percent growth in demand, realizing the Plan B efficiency measures alone would lead to a 6 percent decline in global primary energy demand from 2006 levels by 2020. Beyond these productivity gains, because producing power from fossil fuels generates large amounts of waste heat (and wasted heat equals wasted energy), shifting from fossil fuels to renewables, another key step toward stabilizing climate, would further reduce primary energy demand in the Plan B energy economy.